Atmel ATmega32M1 User Manual

262
7647H–AVR–03/12
Atmel ATmega16/32/64/M1/C1
20. Analog Comparator
The Analog Comparator compares the input values on the positive pin ACMPx and negative pin
ACMPM or ACMPMx.
20.1 Features
• 4 Analog Comparators
• High Speed Clocked Comparators
• 4 reference levels
• Generation of Configurable Interrupts
20.2 Overview
The ATmega16/32/64/M1/C1 features 4 fast analog comparators.
Each comparator has a dedicated input on the positive input, and the negative input of each
comparator can be configured as:
• a steady value among the 4 internal reference levels defined by the Vref selected thanks to
the REFS1:0 bits in ADMUX register.
• a value generated from the internal DAC
• an external analog input ACMPMx.
When the voltage on the positive ACMPn pin is higher than the voltage selected by the ACnM
multiplexer on the negative input, the Analog Comparator output, ACnO, is set.
The comparator is a clocked comparator. The comparators can run with a clock frequency of up
to 16MHz (typical value) when the supply voltage is in the 4.5V-5.5V range and with a clock fre-
quency of up to 8MHz (typical value) otherwise.
Each comparator can trigger a separate interrupt, exclusive to the Analog Comparator. In addi-
tion, the user can select Interrupt triggering on comparator output rise, fall or toggle.
The interrupt flags can also be used to synchronize ADC or DAC conversions.
Moreover, the comparator’s output of the comparator 1 can be set to trigger the Timer/Counter1
Input Capture function.
A block diagram of the four comparators and their surrounding logic is shown in Figure 20-1.

Atmel ATmega32M1 Specifications

General

Architecture	8-bit AVR
Flash Memory	32 KB
SRAM	2 KB
EEPROM	1 KB
Clock Speed	16 MHz
GPIO Pins	32
I/O Pins	32
ADC Channels	8
ADC Resolution	10-bit
UART	1
USART	1
SPI	1
I2C	1
PWM Channels	6
CAN	1
Operating Voltage	2.7V - 5.5V
Operating Temperature	-40°C to +85°C
Temperature Range	-40°C to +85°C
Package	44-TQFP, 44-QFN

Summary

Features

AVR CPU Core

Reset and Interrupt Handling

Explanation of interrupt sources, vectors, priority levels, and behavior during interrupt execution.

System Clock

System Clock Prescaler

Details on the CLKPR register for dividing the system clock to reduce power consumption and affect peripheral frequencies.

Power Management and Sleep Modes

8-bit Timer/Counter0 with PWM

Modes of Operation

Detailed explanation of Normal, CTC, and various PWM modes for Timer/Counter0 operation.

Controller Area Network - CAN

CAN Protocol

Explanation of the CAN protocol principles, standards, and message transmission priorities.

Error Management

Description of error detection mechanisms (message and bit level) and fault confinement states.

Analog to Digital Converter - ADC

Features

List of ADC capabilities including resolution, accuracy, conversion time, input channels, and reference voltages.

Starting a Conversion

Procedures for initiating ADC conversions, including single conversion and auto-triggering modes.

debugWIRE On-chip Debug System

Features

Overview of debugWIRE capabilities including program flow control, real-time operation, and symbolic debugging.

Boot Loader Support – Read-While-Write Self-Programming ATmega16/32/64/M1/C1

Self-Programming the Flash

Procedures and considerations for programming the Flash memory using the SPM instruction.

Memory Programming

Program And Data Memory Lock Bits

Fuse Bits

Electrical Characteristics

Absolute Maximum Ratings*

Critical voltage, current, and temperature limits that must not be exceeded for device reliability.

DC Characteristics

Instruction Set Summary

Register Summary